A hard disk device is equipped with a brushless motor for rotating a disk. A conventional brushless motor is disclosed in, e.g., SG185981. A permanent-magnet synchronous motor of SG185981 includes a permanent magnet mounted to at least one of a top yoke and a bottom yoke and an armature arranged within an air gap between the permanent magnet and the other yoke.
In a so-called axial-gap-type motor in which an armature and a permanent magnet are axially opposed to each other, it is sometimes the case that a coil and an electronic circuit for supplying a drive current to the coil are formed in a single circuit board. In this case, it is required that the circuit board be firmly fixed to a base in order to accurately maintain the axial distance between the coil and the permanent magnet.